1. Field of the Invention
The present invention relates to a paper-making process, in particular, to that having an excellent effect for improving retention of fillers and fine fibers in paper-making industry.
2. Description of the Background Art
In the paper-making industry, for manufacturing printing papers, industrial papers, etc. various fillers such as kaolin, clay, talc, titanium dioxide, calcium carbonate or urea resins are added for the purpose of improving the whiteness, opacity, printability, etc. of papers to be formed. Various means of improving the retention and fixability of fine fibrous materials have heretofore been effected for the purpose of improving the retention of the fibrous materials and the yield of the paper products and of reducing the load of treating the white water and waste water to be drained from the paper-making process.
As the retention-improving agent which has heretofore been employed for the said purpose, there are mentioned inorganic compounds such as aluminum sulfate as well as water-soluble high polymer compounds such as polyethyleneimine, polyamine, epichlorohydrin-modified polyamidepolyamine or non-ionic or ionic polyacyrlamide derivatives.
However, even though such retention-improving agent is used, a sufficient effect could not still be obtained on the following reasons:
(1) Improvement of retention of fillers and fine fibers in the paper-making step. PA0 (2) Stability of retention under high shearing condition in the paper-making step. PA0 (3) Stability of retention under the condition of closed water system. PA0 (4) Reduction of the load for recovery of white water and for treatment of waste water drained. PA0 (5) Reduction of abrasion of paper-making wires.